What Is Floor Joist? Can You Use 2×6 For Floor Joist?

Kasfi Anan October 26, 2023 Flooring

Nowadays floor joists are adopted to support the floor more specifically which can extend over an open space. Floor joists complete the upper floor of a house. Each floor joist is built by placing them evenly spaced and parallel. But this expects large openings on the underside of walls or structural beams.

If you want to use 2×6 for the floor joist, then that is possible but need to know about floor joist, joist span & span size, and how and when to choose a 2×6 joist for the hardwood floor. No worry! You will know the details in the next parts of my writing.

What Are Floor Joists & Spans?

A floor joist is a horizontal structural member that provides support to the floor and helps distribute the weight of the building and its contents to the foundation or load-bearing walls. Floor joists are typically made of wood, engineered wood, or steel, and they span between walls or beams to create a framework for the floor above.

The primary function of floor joists is to bear the load from the floor and transfer it to vertical supports such as beams, walls, or foundations. They also help to distribute the load evenly, preventing sagging or excessive deflection on the floor.

The size, spacing, and material of floor joists depend on various factors regarding the design requirements, building codes, and the expected load that the floor will experience.

Floor joists are typically arranged parallel to each other and spaced at regular intervals. The spacing between joists varies depending on factors such as the type of construction, the load requirements, and the span length.

Commonly used joists are spaced at 16 inches (40.6 cm), 19.2 inches (48.8 cm), or 24 inches (61 cm) in the center.

On top of the floor joists, additional layers such as subflooring and flooring materials are installed to create a sturdy and functional floor.

Can You Use 2×6 for the Floor Joist? But When and Where?

While 2×6 lumber can be used as floor joists in some situations, it may have limitations compared to larger joist sizes. Generally, 2×6 floor joists are more commonly used for shorter spans and lighter loads. They are suitable for smaller rooms or low-traffic areas where the load requirements are not excessive.

Is 2×6 good for floor joists? Well, it depends. Your floor joists must be of sufficient size to support the load of your floor. If this target is fulfilled, then it is possible to use 2×6 for floor joists.

When using joists, spot them very close together to make the floor much stronger.

2×6 lumber can also be usable for the floor joists.

If floor joist spans are less than 10 to 12 feet, 2×6 lumber should be used.

For longer spans or areas with heavier loads, larger and stronger joists, such as 2×8, 2×10, 2×12, or engineered wood joists, may be required. This type of joist ensures adequate structural support and prevents excessive deflection or sagging of the floor.

How Much Weight Can 2×6 Floor Joists Hold?

The amount of weight that 2×6 floor joists can hold depends on several factors such as the species and grade of the lumber, the span or distance between supports, the spacing of the joists, loading conditions, and treatment (if pressure-treated).

In the United States, the span tables and load-bearing capacity of lumber are typically provided by organizations like the American Wood Council (AWC) or local building codes.

A typical 2×6 floor joist made of #2 Southern Pine (a common type of construction lumber) can support a live load (the weight of people and furniture) of about 40 pounds per square foot (psf) over a typical 10-12 foot span when the joists are spaced 16 inches on center.

Here’s a summary of the weight that a 2×6 can hold, whether used as a floor joist or when oriented horizontally.

2×6 Floor Joists:

General untreated 2×6 joists are used to support a live load of around 53 pounds per linear foot according to building codes. This means an 8.5-foot length could support approximately 450 pounds across that length for residential applications.
However, a 2×6 can support more weight before failing, but the aim is to design it to prevent failure.

2×6 Oriented Horizontally:

How much weight can a 2×6 hold horizontally (edge)? When a 2×6 is used horizontally (on edge), the compressive strength applied parallel to the grain varies depending on factors like wood species and quality.

The compressive strength parallel to the grain can range from approximately 1,097 to 1,649 pounds per square inch (psi).

Pressure-Treated 2×6:

Pressure-treated 2×6 wood is used for outdoor applications and is designed to resist insects and rot.

For structural purposes, pressure-treated lumber on edge like untreated wood, is considered to support around 53 pounds per linear foot according to building codes.

How Can You Strengthen 2×6 Floor Joist?

Boost the spacing between joists

Add block in the joists
Install metallic or wooden bridging
Expand sister joists to the existing shafts

You can rebuild the occurring joists with bigger ones
Strengthen a second layer of joists & then attach a beam for additional support

What Is The Maximum Span for A 2×6 Joist?

The Maximum Length A 2×6 Can Span:

A floor joist, it is 6’-10” and 12’-6”.

When it comes to the ceiling joist, is 20’-8”.
As a deck joist that is 9’-11”.
The deck board is 24′.

Perfect Lumber Size for Floor Joists:

2×6 joists spaced 10 inches in the center
2×8 joists spaced 12 inches in the center
2×10 joists spaced 16 inches in the center

2×12 joists spaced 24 inches in the center
4×8 joists spaced 24 inches on the center
4×10 joists spaced 30 inches on the center

4×12 joists spaced 36 inches on the center

What Is The Best Way to Support Your 2×6 Ceiling Joists to Support a 2nd-floor Bedroom and Bathroom?

Supporting 2×6 ceiling joists to support 2nd-floor bedrooms and bathrooms will cost you a lot, hire a good engineer, and find a good contractor. But if you want to try it yourself, you must take proper protection.

All other joists must be sisters.

It should be properly attached with the help of glue and screws otherwise various problems may occur.
You can also use steel joist hangers if you prefer, such hangers can provide the required support for the joists.
Fastening to wall studs is possible with bolts or screws.

And most importantly, all these things need to be done depending on the size of your span.

2×6 Floor Joist Span Chart

Floor Joist Spacing (Inches)	Species of Wood Should Use	Grade	2×6 Span (ft-in)
12	Douglas fir-larch	SS	12 to 6
12	Douglas fir-larch	#1	12 to 0
12	Douglas fir-larch	#2	11 to 10
12	Hem-fir	SS	11 to 10
12	Hem-fir	#1	11 to 7
12	Hem-fir	#2	11 to 0
12	Southern Pine	SS	11 to 10
12	Southern Pine	#2	11 to 3
12	Spruce-pine-fir	#1	11 to 3
12	Spruce-pine-fir	#2	11 to 3
24	Douglas fir-larch	SS	9 to 11
24	Douglas fir-larch	#1	9 to 7
24	Douglas fir-larch	#2	9 to 3
24	Hem-fir	SS	9 to 4
24	Hem-fir	#1	9 to 2
24	Hem-fir	#2	8 to 9
24	Southern pine	#1	9 to 4
24	Southern pine	#2	8 to 6
24	Spruce-pine-fir	#1	8 to 11
24	Spruce-pine-fir	#2	8 to 11

2×6 Floor Joist Price Chart

Price of an 8′ 2×6	$6.76
Price of a 10′ 2×6	$10.98
Price of a 12′ 2×6	$11.42
Price of a 16′ 2×6	$17.54

2×6 Or 2×8 For Floor Joists: What Should I Choose And Why?

Whether you choose 2×6 or 2×8 for your floor joists depends entirely on the specific needs of your project. Generally, 2×8 joists are best for spans greater than 12 to 14 feet. And for spans less than this, 2×6 joists are usable.

Scene-01: 2×8 joists are good for long spans and support the extra weight. On the contrary, 2×6 joists are not able to support much weight compared to that. Also, they are much less expensive than 2×8 joists. So, if you want a joist that can boost a fair amount of weight and is less expensive, then 2×6 joists are a perfect choice for you.

Scene-02: Similarly, 2×8 joists are applied to support heavy weights and afford the additional cost. Also, 2×8 joists are more commonly used in high constructions and multi-story buildings. From that point of view, 2×6 joists may be a more cost-effective option when building single-story residences, shops, or garages.

The Most Common Lumber Size for Floor Joists

What size wood for floor joists? The most common lumber sizes for floor joists in the United States are 2×6, 2×8, 2×10, and 2×12.

Among these options, the 2×10 joist is considered the workhorse of the group. It strikes a balance between strength and cost, thus it is a popular choice for many residential construction projects.

Choosing the Right Joist Size

2×6 Joists:

These are used in situations where the span between supports is relatively short.
They are suitable for smaller rooms or home additions with a span of up to 12 feet and 6 inches.
Keep in mind that 2×6 joists are not the best choice for heavy loads or larger areas.

2×8 Joists:

These are a step up in terms of load-bearing capacity.
They can span up to 14 feet, so it is a good choice for mid-sized rooms.
If you plan to install hardwood flooring in a larger space, 2×8 joists might be a better option.

2×10 Joists:

As mentioned earlier, 2×10 joists are versatile and commonly used.

They can span up to 21 feet, which makes them suitable for a wide range of flooring applications like hardwood.
This size is the “go-to” choice for many residential flooring projects.

2×12 Joists:

When you’re dealing with a substantial span or very heavy loads, 2×12 joists are your best bet.

They can span up to 24 feet.
It is ideal for larger spaces and attic flooring, especially if you plan to use it for storage or conversion into living space.

Specifics for Hardwood and Attic Flooring

Hardwood Flooring:

Solid wood flooring is a popular choice for its durability and timeless appeal in hardwood flooring. But you can also use quality engineered wood flooring as they are quite versatile and sometimes even more aesthetics than cheap wood.

When installing hardwood flooring, it’s essential to consider the joist size carefully.

For most hardwood flooring applications, 2×10 joists are sufficient, as they provide the necessary support for the flooring while ensuring a stable and level surface.

However, if you’re installing hardwood in a particularly large room, you should consult a structural engineer to ensure the joists can handle the extra weight.

Attic Flooring:

Attics are often used for storage or even as additional living space. You can use solid wood or engineered wood like ply or OSB for attic flooring.

If you’re planning to use your attic for storage, 2×10 or 2×12 joists are standard, as they can support the weight of stored items.

If you’re considering converting your attic into a living space, you’ll likely need larger joists, then the specific size will depend on the span and intended use.
Consulting with a structural engineer is highly advisable when converting an attic. Because they can only provide guidance tailored to your unique circumstances.

Helpful Articles:

Frequently Asked Questions:

Can You Use a Sistered 2×4 as The Subfloor in Your Tiny House?

Sistered 2×4 as the subfloor is usable in your tiny house. It is important to use proper construction techniques when undertaking this task. Both boards should securely fasten together at the edges, joists, and all points. A more vertical installation will give you better output. When using a sistered 2×4 as the subfloor, review that it is completely flat. Be sure to use screws or pins for a secure connection.

How Wide Should Deck Joists Be?

2×6 joists: Joists span should be 9 1/2′.
2×8 joists: Joists span should be 13′.

2×10 joists: Joists span should be 16 1/2′.

Could You Use 2×4 Floor Joists With a Center Beam to Half The Spans?

It is possible to use 2×4 floor joists with a center beam to half the spans. But you should evaluate the weight of the floor, the load of the beam, and all other weights correctly, in this case. It is best to use slightly larger joists based on the size of the span and the weight of the floor.

What Are The Thinnest Floor Joists?

Steel channel joists

Metal web joists
Laminated veneer lumber joists
Truss joists

I-joists
Open web joists
Parallel chord trusses

Glulam joists

EndNote about Floor Joist and Its Size

Finally, floor joist & structural span installation is a highly professional job, it is not a DIY job for all. So, if you are not a pro & experienced one, please do not try it, it is not a piece of cake to do.

Hope you got to know all the important and necessary information about the 2×6 floor joists. Apart from that I have discussed various important issues with 2×8 floor joists. Moreover, other effective solutions & ideas given through various FAQs will be very useful in your real life.